Hello kirt, I am also trying to use HNA. I contacted with Shipley and they have S1818 and S1827. Will they work as HNA mask and can you suggest a receipt? >> I am trying to isotropically wet etch silicon using a >> 126:60:5 HNO3:H20:NH4F >> etchant (as described by Williams and Muller, J. of MEMS >> 1996). The etchant >> appears to work well, but masks made of AZ5214 do not. In less than >> 15 minutes, the AZ5214 layer has visibly thinned and formed holes. >> >> Can anyone recommend a more durable mask (PR, metal, both or >> otherwise) for this etchant? kac> In my measurements with this etchant the photoresist etch rate was zero kac> (or it might have even swelled slightly). kac> Try OCG (formerly KTI) 820 or similar in this series of resists kac> or kac> Shipley Microposit 1822 or similar in this series. kac> Silicon dioxide is slowly etched. kac> Silicon nitride is barely etched. kac> Titanium is etched. kac> Chromium is not etched. kac> --Kirt Williams Agilent Technologies kac> _______________________________________________ kac> mems-talk@memsnet.org mailing list: to unsubscribe or change your list kac> options, visit http://mail.mems-exchange.org/mailman/listinfo/mems-talk kac> Hosted by the MEMS Exchange, providers of MEMS processing services. kac> Visit us at http://www.mems-exchange.org/ Best regards, Weili mailto:weili@seas.ucla.edu ---- Weili Liu 14-124 Engineering IV Department of Mechanical and Aerospace Engineering University of California-Los Angeles 420 Westwood Plaza, Los Angeles, CA90095 Tel: 310-825-7457 Fax: 310-206-2302